This problem has been bothering me for quite some time, and I couldn't pinpoint exactly what it was. I have Accordance 10.4.1, Windows Vista and Thinkpad R500. The touchpad has a horizontal and vertical scroll lines. Whenever I touch the horizontal scroll, all open windows in accordance suddenly disappear and all is left is the grey background. The windows come back when I change the size of the main window (maximize, restore etc). Even the most minimal unintentional contact with the horizontal scroll area causes all open sources to disappear. Occasionally this happens when other parts of the touchpad are touched, but it is most consistent with the horizontal line. I would greatly appreciate if someone could look into it.